Send CANCEL to call with early media (PROGRESS INBAND).

This is imported from branch "invitestate" and "invitestate-1.4"

***
***
*** IF YOU HAVE ISSUES WITH BYEs/CANCELs - PLEASE UPDATE AND TEST AGAIN!
*** 	Thank you!
***
***

/Olle


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@48216 65c4cc65-6c06-0410-ace0-fbb531ad65f3